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Installation of new MPR

Installation of new MPR. Harald Lück ILIAS WP1 meeting, June 14th 2005. Old MPR: T=1.35%. New MPR: T ≈ 900ppm. Timeline of MPR exchange. 02.05: Opened vacuum vessel & exchanged MPR 03.05: Installed attenuator. Prealigned MPR ….spent some time with aligning 09.05 Ifo aligned and flashing

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Installation of new MPR

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  1. Installation of new MPR Harald Lück ILIAS WP1 meeting, June 14th 2005

  2. Old MPR: T=1.35% New MPR: T≈ 900ppm

  3. Timeline of MPR exchange • 02.05: Opened vacuum vessel & exchanged MPR • 03.05: Installed attenuator. Prealigned MPR • ….spent some time with aligning • 09.05 Ifo aligned and flashing • 12.05 stable PR Michelson lock • 19.05 1hour 2f lock @ 3.5kHz • 22.05 tuned down to 1kHz

  4. Power in PR Cavity • Input power: 1.7W incident to MPR. • Old MPR (1.35%) ≈ 500W ≈ 1.7 * 4/ 1.35% • New MPR: up to 2kW (normally ~1.5kW) • Expected PR factor >2000 ↔ 3.4kW • Have not yet determined where we lose the power (→Stefan)

  5. Power measurements • Power transmitted through mirrors • MFE: 13mW/10ppm → 1.3kW • MFN: 11mW/10ppm → 1.1W 10ppm for MFN guessed to be the same as MFE • BS AR ca. 30mW/44ppm → 1.4kW • MCN, MCE very high losses due to lens

  6. Cavity pole measurement Curve fit gives: 15.14 Hz +-0.15 Hz Simulations with 126ppm transm. for MCE/N, 50ppm for MFE/N, and 200ppm for BS/AR. BS thermal lens set to 10k for new configurations give a pole f of 15 Hz.

  7. Simulations Fit pole freq: 141Hz ----------------------------------------------------------- pole freq: 18.4 Hz------------------------------------------------------------ pole freq: 15.0 Hz

  8. Transfer function with old MPR (1.35%) Fit gives 147Hz pole frequency

  9. Wire attenuator, 15µm glas fibre, 0.3% attenuation/round trip Not needed with the present losses

  10. Wire attenuator in front of MPRr

  11. Thermal lensing in BSoutput mode pattern Directly after relocking f=20km A few minutes after relocking f= 8km

  12. Building up the thermal lensdark port power after relocking for PR and DR Michelson

  13. Increasing ROC heater powerdual recycled lock, 1kHz detuned Dark port power 90W 75W 80W 85W 98W PR cavity power

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